Manuscript differences in accentuation

Even a cursory look at one psalm reveals differences in the te'amim written in the text over the centuries. I have been verifying the presence of the metheg in a few verses. So far my program's fuzzy logic (to avoid the premature return to the tonic that it causes in the music) is performing very well. Most methegs I have seen are on the first syllable of a word -- generally unaccented. And my program correctly ignores them.

Psalm 26:12 is an example. The first image is the Aleppo codex as reconstructed on the mgketer.org site. Here is the clear text for Psalm 26:12 -- the first two words. It is clear from the text that it begins on the third degree of the scale (g = tifha = median) and moves to the fifth degree (B = munah = dominant) on the last syllable. Do you see how easy this is to sight read?

The first two words of Psalm 26:12 -- no metheg

The music as derived by Suzanne Haïk-Vantoura from the Letteris Edition (19th century) is in the image below. 

Suzanne Haïk-Vantoura handwritten Psalm 26:12.

In the image above, the little stroke under the a (ayin is carrying the a) is a metheg -- not a musical instruction. It should be ignored. It is not a silluq -- signifying a return to the tonic. It is not an accent. It gives a false emphasis to an 'upbeat' in the music. The metheg is an aid to pronunciation of the vowel. This particular error is of little significance since it is immediately followed by a change of reciting note.

The first two words of Psalm 26:12 Westminster Leningrad Codex

The output of my program correctly ignores the metheg in the WLC (seen in the Hebrew above). It produces the music as for the Aleppo Codex text above.

An observation of the Letteris shows other differences in accentuation from the Aleppo Codex and the WLC. Maybe one day some official site will write the programming to do the music from their textual versions. You can compare the text at the links. And report your observations in a comment -- love to hear from you :).